The Barnes’ Notes on the Bible asserts: “The most natural construction of this Greek phrase would be to refer it to years. The Latin Vulgate interprets it in a similar way - et septem tempora mutentur super eum - “And let seven times be changed” or revolve “over him.” In the Codex Chisianus it is: καὶ ἐππὰ ἔτη βοσκηθῆ σὺν αὐτοῖς kai hepta etē boskēthē sun autois - “and let him feed with them seven years.” Luther renders it “times.” Josephus understands by it “seven years.” - “Ant.” b. x. ch. 10: Section 6. While the Chaldee word is indeterminate in respect to the length of time, the most natural and obvious construction here and elsewhere, in the use of the word, is to refer it to years. Days or weeks would be obviously too short, and though in this place the word “months” would perhaps embrace all that would be necessary, yet in the other places where the word occurs in Daniel it undoubtedly refers to years, and there is, therefore, a propriety in understanding it in the same manner here.”
Like Barnes said, Josephus (Antiquities of the Jews, X:X:6) considers these ‘seven times’ as ‘seven years.’ Theodotion of Pontus (2nd century), between the years 180 and 182 C.E., translated the expression as “seven years” (heptà étē). Similarly, other Jewish commentators did.
Between the modern translations which render ‘years’ we have:
The New American Bible : “Till seven years pass over him [you].” (Daniel 4:13, 20, 22, 29)
A New Translation, by James Moffatt.
The Complete Bible—An American Translation read “seven years.”
Good News Bible (1976).
The New Jerusalem Bible, on the note at the verse: “Here the ‘times’, or indeterminate periods’ are probably ‘years’”. (In the same manner does, the translation La Bibbia - Civiltà Cattolica, Piemme, 1983, an Italian Catholic Bible)
Moreover, I’ve found an interesting citation about the Nebuchadrezzar’s disease period. A fragment of tablet - B[ritish] M[useum] 34113 (sp 123), published by Albert Kirk Grayson [in his text Babylonian Historical-Literary Texts (“Toronto Semitic Texts and Studies”, no. 3; Toronto, University of Toronto Press, 1975, pp. 87-92)] partly says:
2 [Nebu]chadnezzar considered
3 his life appeared of no value to [him]
11 He does not show love to son and daughter […]
12 […] family and clan do not exist […]
14 His attention was not directed towards promoting the welfare of Esagil [and Babylon].
Granted, this isn't a decisive proof, but seems to me this monarch had in a life period of him - really - a very weird behaviour...